Example showing the effect of the aperture sizes on the extraction of a 1D spectrum from a MUSE data cube. Top: Spectrum of the same member of the cluster SDSS 2222, extracted using circular apertures of radius 1.4″ (blue), 0.6″ (orange), and 0.3″ (red). Bottom: Ratio between each spectrum and the one extracted with the 0.3″ aperture. A bigger extraction aperture produces a bluer spectrum (namely, the spectrum shows a larger flux at lower wavelengths).